With the election just days away, Senator Scott Brown campaigned in Boston’s North End Friday with Rudolph W. Giuliani, former New York City mayor and fellow Republican. Their visit drew a large crowd of supporters, who accompanied Brown down Hanover Street, chanting “Go, Scott, go!”

At a brief rally near the Greenway, Brown introduced Giuliani as “America’s mayor.” Giuliani recalled stumping for Brown during his victorious 2010 campaign and said Brown had “kept his promise” to be a moderate, bipartisan voice in Congress.

“That’s not always the case in politics,” he said to cheers. “We know that.”

Later on Friday, Senate challenger Elizabeth Warren delivered her stump speech from a boxing ring at Ramalho’s West End Gym in Lowell, to a large and enthusiastic crowd. A ­Warren campaign poster was tacked to a wall beneath a sign meant for boxers, which read: “No Pain, No Gain.”

“Families in Massachusetts need a fighter in their corner,” Warren told the boisterous ­audience. “I want to go to Washington to be that fighter.”

ESSDRAS M SUAREZ/GLOBE STAFF

Challenger Elizabeth Warren spoke to a Ramalho’s West End Gym crowd in Lowell.

She ended her speech with a call for campaign volunteers, and then shouted her biggest applause line of the night: “With four days left, are you ready to do this?”

She shook hands with the ringside crowd as “Eye of the Tiger,” theme song from “Rocky III,” blared from the audio system.

With days left in their long, exhausting, and expensive race, the candidates for US Senate are cranking up the intensity of their get-out-the-vote ­efforts with emotional events aimed at energizing supporters for the hard work of door-knocking and cold-calling voters over the final days of the race.

Campaigning with Brown, Giuliani denounced Warren as an uncompromising liberal who would raise taxes, increase spending, and be a “force for partisan gridlock in Washington.”

“She’s so far on the fringe, she’s fallen on the cliff,” he said, drawing laughter from the crowd.

Brown said he would work to improve the economy and rein in the government’s “serious spending problem.”

“People are hurting, but they want to take more of your hard-earned money,” Brown said. “That money should stay right here in the North End.”

A crowd of Warren supporters stood nearby, holding signs and getting some honks from passing drivers.

Brown and Giuliani then walked down Hanover Street, stopping periodically to shake hands and sign autographs or to pop into a business to greet the owners. At Modern Pastry, a well-known bakery on ­Hanover Street, they both tasted cannoli, and down the street at Mike’s Pastry, Brown ordered an M&M cookie.

In ­Lowell, the gym’s owner, ­Arthur Ramalho, a Warren supporter who has trained boxers for 45 years, told the crowd, “I trained a lot of champions in my day, and our next champion is going to win a US Senate race.”